Military Study Plots Defense Against Jet Lag

A Navy sleep researcher has found ways to manage some of the effects of jet lag--including reaction times and short-term memory problems--by controlling the environment in a plane cabin and feeding passengers large doses of a sleep-inducing substance found in protein-rich foods.

The research was commissioned by the commandant of the Marine Corps, who wants troops being rushed to far-away trouble spots to be well-rested. The findings also could have applications for commercial airline companies, the researcher said.

Cheryl Spinweber, a psychologist for the Naval Health Research Center, conducted the experiments last year with Marines on 15-hour flights from Camp Pendleton to Okinawa, Japan.

During a preliminary study, Spinweber discovered that the Marines slept an average of two hours during the 17-hour trip, which included a two-hour layover in Alaska.

“What we found in the pilot study was that these Marines didn’t sleep on the plane if left to their own devices and they arrived very tired,” she said.

But on the next trip, Spinweber controlled the airplane cabin. She banned beverages with caffeine, set the lighting, controlled the opening and closing of window shades and rescheduled meals and movies to provide long periods of time when the Marines could sleep undisturbed.

She also fed half of the group of 50 two grams of l-tryptophan--an amino acid found in foods such as steak, turkey and milk that contain protein--on the plane and another two grams before they went to sleep in the Okinawa barracks. The other half of the group received a placebo.

Sleep research conducted in laboratories by Spinweber and others has shown that l-tryptophan makes people sleepy without knocking them out. Unlike sleeping pills, the substance does not leave them groggy or unable to wake up suddenly because it does not work on the central nervous system, Spinweber said.

“It’s a mellow pill. It mellows your awake state. It doesn’t knock you out like a sleeping pill would.”

Under Spinweber’s care, the Marines slept like babies. The placebo group slept an average of 291 minutes on the plane, and the l-tryptophan group slept an average of 324 minutes. Some Marines slept nearly every minute of the eight sleeping hours available, she said.

Moreover, the l-tryptophan group slept 52 minutes more in the Okinawa barracks than the group which received the placebo. “The point I always like to make is that an hour of sleep doesn’t sound like a lot of sleep, but it is a lot of sleep,” she said. “Getting an hour of sleep makes people feel much, much better.”

In tests the next day, the Marines showed better reaction times and better short-term memory. Spinweber attributed the improvements to their increased sleep.

However, the extra sleep did not improve the troops’ marksmanship or mathematical ability. Spinweber believes that those skills may be thrown off by other factors involved in jet lag, such as desynchronization of the body’s 24-hour clock and dehydration caused by flying in a pressurized cabin.

Spinweber, who also is taking part in an international study of sleeping patterns of pilots on long-haul commercial flights, said her research could be helpful if an airline wanted to set up an anti-jet lag compartment or special flights for business executives who cannot let jet lag affect work.

The average tourist, however, can get more sleep by following these tips:

- Tell flight attendants not to disturb you.

- Wear sleeping shades that block out light.

- Remain well-hydrated. Don’t consume alcohol or drinks with caffeine.

- When arriving, don’t take a nap. Stay awake until it is the appropriate time for sleep in the country you have arrived in.